Re: [Xen-devel] [RFC 3/4] HVM x86 deprivileged mode: Code for switching into/out of deprivileged mode

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.08.15 at 17:07, <tim@xxxxxxx> wrote:
> At 14:53 +0100 on 17 Aug (1439823232), Ben Catterall wrote:
>> So, have we arrived at a decision for this? Thanks!
> 
> Seems to have stalled a bit.  OK, I propose that:
>  - we use TR/IST to make Xen take interrupts/exceptions at a different SP;
>  - we make that SP be an extension of the main stack, so that things
>    like current() Just Work[tm];
>  - we set this up and tear it down when we enter/leave depriv mode.
>  - someone ought to look at the case where IST handlers copy
>    themselves to the main stack, and see if we need to adjust that too.
> 
> Any other proposals?

No.

> I think we can leave the question of TR switching on VMEXIT as a
> separate issue.

Just like for the other one - at this point I think anything that work
should be okay. Dealing with quirks can be deferred (but it would
be nice if a respective note was added in a prominent place so it
doesn't get forgotten once/if these patches leave RFC state).

Jan


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